The technology of the present disclosure relates to an image forming apparatus and an untransferred toner recovery device installed therein.
In an image forming apparatus, when toner attached to an electrostatic latent image of a photosensitive drum is transferred to a recording paper, a part of the toner remains on the photosensitive drum after the transfer. The untransferred toner is removed from the surface of the photosensitive drum by a cleaning unit and is collected in a recovery container of an untransferred toner recovery device as waste toner. When the recovery container is fully filled with the untransferred toner, the recovery container is exchanged to an empty recovery container.
There has been proposed an untransferred toner recovery device in which a conveying stirring screw and a float plate have been disposed in the recovery container. In the untransferred toner recovery device, collected untransferred toner is conveyed by the conveyance stirring screw and is stirred to be unifomized, and when the float plate is pushed up by the untransferred toner increased with the passage of time, a photointerrupter is configured to detect this fact and detect that the amount of collected toner has reached a predetermined amount.